[26.07] The Luminous Type Ic SN 1992ar at z=0.145

SN 1992ar at z=0.145 was one of the most distant and
brightest SNe discovered by the Calán/Tololo Survey.
Surprisingly, its spectroscopic type was not Ia but Ic.

This SN illustrates many of the challenges faced by the
detailed study of individual SNe at moderately large
redshift. These are, among others, the loss of features in
the red part of the spectrum due to universal expansion, and
K--corrections strongly varying in time which
determine the shape of the light curve in the rest frame of
the SN. It illustrates, as well, the necessity of spectra
with better S/N ratio than typically obtained with 4m class
telescopes.

In addition, SN 1992ar exemplifies the problem of
contamination faced by the high z Type Ia SNe samples, whose
luminosity distances are used to determine the cosmological
parameters of the Universe. It proves that there are SNe
which are as bright as a Type Ia SN and have a similar light
curve near maximum light, but have different intrinsic
colors, different color evolution, and do not follow the
Light Curve Shape--Luminosity relation used to calibrate the
intrinsic luminosity of a Type Ia event.

We discuss the effect that these luminous Type Ic SNe, if
not removed from the High--z Type Ia SN samples, would have
on the measured cosmological parameters. We also present
observational criteria to distinguish the two different SN
types when the SiII 6355 line is redshifted out of the
sensitivity range of typical CCD detectors.